INCORRECT BILLING ON UPGRADE...AGAIN

I phoned ********** 667 on the 15th of February 2018 and spoke to Kreshan (excuse spelling) for an upgrade. Wanted to upgrade to the iphone 8, 64gb that was on promotion for R519 per month for 36 months. Have now received my bill and it's for R819!!! Reference ********** . Have spoken to a Gregory this morning who confirmed this was billed incorrectly. Kreshan doesn't even have the decency to phone me back and correct his mistake. I welcome you to listen to the recording...you will see who's at fault. This is the last time I am upgrading with MTN. Every single time (and yes, you are welcome to look at the history) I have problems with *********** service and incorrect billing. I am not even joking. Sort this out NOWWWWWWWWW. Tired of your pathetic frustrating service.